The invention relates to the field of the simulation of geological processes for studying the subsoil. Interest is particularly focused on the karstification phenomena in a karstic region.
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section. Furthermore, all embodiments are not necessarily intended to solve all or even any of the problems brought forward in this section.
Karstification of a rock is the phenomenon whereby this rock is fashioned by the dissolution of carbonates in water. The water infiltrates through interstices of the rock, for example pores or fractures, and this infiltration increases the size of these interstices by virtue of the dissolution of carbonates of the rock in the infiltrated water. Conduits and cavities can thus be formed.
The water may typically be rainwater made acid by carbon dioxide from the atmosphere or the ground. The water may, among other things, originate for example from hydrothermal lifts.
The rock may, for example, comprise limestone.
In carbonate reservoirs, karst processes are frequently observed. These processes have a clear impact on reservoir flow performances and predictions: some distant wells could be connecting extremely fast while other close wells could be not effectively connected. For this reason, to get a precise picture of the potentiality of a reservoir, it is important to address simultaneously two different objectives:                the appropriate representation of karst conduits network which controls the connectivity of the reservoir;        the formalization of a framework to address uncertainties on global connected volumes and related local heterogeneities location.        
It is known practice to model a karstic region statically, by using observations, in particular geological and seismic observations. When drilling a well, data measured via the well, called well data, can be used to make a posteriori adjustments to the model of the karstic region.
The article by O. Jaquet et al, “Stochastic discrete model of karstic networks”, Advances in Water Resources 27 (2004), 751-760, describes a method for simulating karstification phenomena based on a stochastic approach. In this work, a karstic region is modeled as a network of pipes with permeabilities and porosities depending on particles traveling through these pipes. These particles are corresponding to water droplets introduced in karstic system, and their displacement over the network is subjected to laws of “random walk” type. This method could be named as a pseudo-genetic approach.
There is a need to improve the efficiency of the determination, to provide fast and efficient geometrical techniques to distribute conduits zones consistently with paleo-aquifers infiltration and outlet regions, with reasonable CPU performance.